Social media can be a powerful tool for embarrassing yourself or sharing your selfies or pics of your kids or pets or sometimes to shine a light on a really important cause. Tonight we're bringing you the story of nearly 300 schoolgirls who were kidnapped halfway around the world and how Hollywood stars are helping the desperate search to save them. It is the rallying cry going viral tonight. "Bring back our girls." From Kerry Washington to Amy Poehler to Chris brown. Celebrities joining the global outrage. Pleading for the safe return of nearly 300 Nigerian girls kidnapped from their school in the middle of the night. Loaded onto trucks, taken hostage by militant islamist gunmen who are now threatening to sell them into slavery. For weeks the girls were missing with little attention paid outside Nigeria. We're wearing red in solidarity with the women in -- Reporter: Until this woman noticed a small news item. I was looking on Facebook and Twitter to see if anybody was talking about it and I & people were not talking about it. There were a few people who had mentioned it who were Nigerian and were posting about it. But other than that, no one in the United States or in Europe had made any calls. Reporter: So L.A. Director Rama mosley created this Facebook page. Bring back our girls. This has consumed my life. And I believe it will until the girls are rescued. Reporter: The message caught like wildfire. In just over a week it's received more than 30,000 likes. On Twitter, the hashtag has been used more than 800,000 times. And it has ignited a fury toward this man, the face of evil. Responsible for their kidnapping. He is the leader of the islamist terrorist group boko harm, which means "Western education is a sin." Watch as he smiles and threatens their lives. "I took your girls. They are our slaves. I will sell them in the market." Boko haram's targets -- schools and children who want to learn. The group is already responsible for dozens of massacres, including the slaughter of 50 schoolboys earlier this year. Tonight the world watching, mall Yousafzai and Hillary Clinton speaking out in horror as the families ache for the safe return of their children. These girls seen here among some 50 who did manage to escape. In Nigeria desperate marchers in the streets angry their government hasn't done more. The president promising today the girls will be found. The U.S. Offering to help with the search and supply intelligence. Bring back our girls! Reporter: Tonight these demonstrators in Los Angeles rallying for the girls to be brought home. As the global push grows ever louder.

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